Update almost all tests (except co19) to use the new try-catch syntax.

tests/corelib/string_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // TODO(ngeoffray): test String methods with null arguments.
 class StringTest {
 
   static testMain() {
     testOutOfRange();
     testIllegalArgument();
@@ skipping 10 matching lines @@
     testCompareTo();
     testToList();
     testCharCodes();
   }
 
   static void testOutOfRange() {
     String a = "Hello";
     bool exception_caught = false;
     try {
       var c = a[20];  // Throw exception.
-    } catch (IndexOutOfRangeException e) {
+    } on IndexOutOfRangeException catch (e) {
       exception_caught = true;
     }
     Expect.equals(true, exception_caught);
   }
 
   static testIllegalArgument() {
     String a = "Hello";
     bool exception_caught = false;
     try {
       var c = a[2.2];  // Throw exception.
       Expect.equals(true, false);
-    } catch (IllegalArgumentException e) {
+    } on IllegalArgumentException catch (e) {
       exception_caught = true;
-    } catch (TypeError e) {  // Thrown in checked mode only.
+    } on TypeError catch (e) {  // Thrown in checked mode only.
       exception_caught = true;
     }
     Expect.equals(true, exception_caught);
   }
 
   static testIndex() {
     String str = "string";
     for (int i = 0; i < str.length; i++) {
       Expect.equals(true, str[i] is String);
       Expect.equals(1, str[i].length);
@@ skipping 236 matching lines @@
     }
     test("abc");
     test("");
     test(" ");
   }
 }
 
 main() {
   StringTest.testMain();
 }